Search

In this study, we investigate the effectiveness of high-pressure annealing (HPA) compared to microwave annealing (MWA) in activating n-type and p-type dopants in germanium. For phosphorus dopants, HPA at 500 °C significantly enhances the activation level, resulting in a reduction of sheet resistance to 120.1 ohms sq.−1and a maximum active concentration of up to 5.76 × 1019P cm−3. Similarly, for boron dopants, HPA at 800 °C reduces the sheet resistance to 80.6 ohms sq.−1and achieves a maximum active concentration that maintains effective doping profiles. Transmission electron microscopy images reveal that the amorphous layers implanted with phosphorus and boron are significantly reduced, indicating that HPA is more effective in achieving solid-phase epitaxial regrowth compared to MWA. HPA demonstrates superior performance in minimizing dopant diffusion and reducing sheet resistance for both phosphorus and boron dopants, making it a preferable method for high-temperature annealing in germanium-based devices.

Coffee is a popular beverage worldwide, but coffee beans can be contaminated with carcinogens. The Ames Salmonellamutagenicity test is often used for analysis of carcinogens for mutagenicity. However, previous studies have provided controversial data about the direct mutagenicity of coffee beans based on Ames test results. This study was conducted to determine the mutagenicity of popular Americano coffee based on results from the Ames test. Coffee samples without additives that were served by five international coffee chain restaurants were subjected to the analysis using SalmonellaTyphimurium tester strains TA98, TA100, and TA1535. The levels of bacterial revertants in samples from coffee chains were lower than the twofold criterion of the control sets, and no significant dose-response effect was observed with or without rat liver enzyme activation. These data indicate that Americano coffees from the selected coffee chains possessed no direct mutagenic activity with or without enzyme activation. These findings suggest a low mutagenic risk from Americano coffees served by the selected coffee chains and support the use of other methods to confirm the nonmutagenicity of coffee products. These results are consistent with most recent epidemiological reports.